Systems for determining the position of a vehicle are known for many years. One such known system makes use of a grid of magnets that is provided in the surface whereon the vehicle moves. The system comprises a plurality of sensors that are able to sense the strength of a magnetic field. The plurality of sensors is arranged in a lateral direction of the vehicle, in order to ensure that a magnet arranged in the ground surface is detected when the vehicle passes over the magnet. The signals from the sensors are periodically sampled and provided to computation means to calculate the position of the sensed magnet with respect to the sensors. The described detection of magnets is usually not sufficient to determine the position, as individual magnets can normally not be distinguished from each other. Therefore, in one prior art system, rotational counters are installed on at least two wheels to keep track of the wheel rotation in order to determine a position change and therewith the position. The detection of the magnets prevents the occurrence of an accumulation of errors in the determination of the position and therefore position drift.
A drawback of this known system is that when the vehicle negotiates a bend, the sensors at the outer side of the bend are undersampling the magnetic field strength, while the sensors at the inner side of the bend are oversampling the magnetic field strength. Although the latter causes less problems with the processing power available to present day digital signal processors, the former causes a deterioration of the accuracy of the determined position when the vehicle negotiates a bend.